The action was "bottom-up", not top down. Pressure came from users, not (solely, principally?) from sites' management. This has been totally mis-represented in the "mainstream media".
Here's a comment I submitted to some friends after seeing and hearing some of the "mainstream" broadcast press coverage, last night:
Caught some of the "mainstream media" reporting on the SOPA/PIPA blackout (including public radio and TV). Universally terrible. Minimally reported, with most of the language making it sound as if the sites are supporting piracy. They aren't defending piracy; they're opposing horribly formulated legislation that lends itself to abuse and censorship, places enormous legal and management burdens on them, and undermines the technical infrastructure and attendant security of the Internet.
(And, to boot, cogent analysis makes good arguments that the legislation won't even accomplish what it ostensibly sets out to do.)
Finally, I'd say that the "tech community" has been seeking dialog and participation. They've found a cold-shoulder. In the face of this -- being ignored and disrespected -- escalation to the "blackout" protest became their one avenue to attempting to gain a seat at the table.
Also, if there's any investigative journalism left at ABC and the like, they should spend some time really looking into the financial claims and mis-representations that have been made.
Tim O'Reilly is owner/CEO of a major publishing house that has a different perspective. He's eloquent and quite tied into the "progressive" technical community. They should talk to him (if they can reach a format he's comfortable with, e.g. not editing his words into a mis-representation -- that's my take on what the mainstream media often do, these days).